Border绘制虚线框（转）

  <Grid>
<Border HorizontalAlignment="Center" VerticalAlignment="Center"
Width="60" Height="30" CornerRadius="5"
BorderBrush="Blue" BorderThickness="3">
<TextBlock Text="aaa" HorizontalAlignment="Center" VerticalAlignment="Center"/>
</Border>
</Grid>

看看效果：

一个中规中矩的实线框，如何改造成我们想要的虚线框哪？

第一个想到的就是修改Border的Brush，来看看这样的xaml：

    <Grid>
<Border HorizontalAlignment="Center" VerticalAlignment="Center"
Width="60" Height="30" CornerRadius="5"
BorderThickness="3">
<Border.BorderBrush>
<LinearGradientBrush SpreadMethod="Repeat" StartPoint="0,5" EndPoint="5,0" MappingMode="Absolute">
<LinearGradientBrush.GradientStops>
<GradientStop Color="Blue" Offset="0"/>
<GradientStop Color="Blue" Offset="0.2"/>
<GradientStop Color="Transparent" Offset="0.4"/>
<GradientStop Color="Transparent" Offset="0.6"/>
<GradientStop Color="Blue" Offset="0.8"/>
<GradientStop Color="Blue" Offset="1"/>
</LinearGradientBrush.GradientStops>
</LinearGradientBrush>
</Border.BorderBrush>
<TextBlock Text="aaa" HorizontalAlignment="Center" VerticalAlignment="Center"/>
</Border>
</Grid>

看看效果图：

因为把Brush修改成斜线的渐变色（蓝色->透明->蓝色），因此总体上看起来就是个虚线，但是在圆角的效果取有些不怎么如意。

再换个思路，更换为使用DrawingBrush：

    <Grid>
<Border HorizontalAlignment="Center" VerticalAlignment="Center"
Width="60" Height="30" CornerRadius="5"
BorderThickness="3">
<Border.BorderBrush>
<DrawingBrush>
<DrawingBrush.Drawing>
<GeometryDrawing>
<GeometryDrawing.Pen>
<Pen Brush="Blue" Thickness="3">
<Pen.DashStyle>
<DashStyle Dashes="3,2,0,2"/>
</Pen.DashStyle>
</Pen>
</GeometryDrawing.Pen>
<GeometryDrawing.Geometry>
<RectangleGeometry Rect="0,0,60,30" RadiusX="3" RadiusY="3"/>
</GeometryDrawing.Geometry>
</GeometryDrawing>
</DrawingBrush.Drawing>
</DrawingBrush>
</Border.BorderBrush>
<TextBlock Text="aaa" HorizontalAlignment="Center" VerticalAlignment="Center"/>
</Border>
</Grid>

看看效果图：

利用Pen的DashStyle可以轻易的实现点划的虚线图，当然也可以轻易实现点点划的虚线，DashStyle的规则为：实线长度，空线长度，实线长度，空线长度…，而实现长度如果为0，就代表点。

不过细看这张图的话，还是会发现一些不和谐的东西，圆角从外侧看，确实是圆的，但是仔细看内侧的话，发现其内侧竟然是个直角。。。

好吧，换个思路，放弃Border了，直接用Canvas，加Rectange:

    <Grid>
<Grid HorizontalAlignment="Center" VerticalAlignment="Center" Width="60" Height="30">
<Canvas>
<Rectangle RadiusX="5" RadiusY="5" Width="60" Height="30"
Stroke="Blue" StrokeDashArray="5,2,1,2" StrokeThickness="2"/>
</Canvas>
<TextBlock Text="aaa" HorizontalAlignment="Center" VerticalAlignment="Center"/>
</Grid>
</Grid>

看看效果图：

看起来还不错，确实是圆角的，不过这后面两个方案也有个明显的缺点，就是无法随着文本框内容的增长而动态的绘制。当然可以用Binding来进一步消除这个问题：

    <Grid>
<Grid HorizontalAlignment="Center" VerticalAlignment="Center" Width="60" Height="30" x:Name="g">
<Canvas>
<Rectangle RadiusX="5" RadiusY="5"
Width="{Binding ElementName=g, Path=Width}"
Height="{Binding ElementName=g, Path=Height}"
Stroke="Blue" StrokeDashArray="5,2,1,2" StrokeThickness="2"/>
</Canvas>
<TextBlock Text="aaa" HorizontalAlignment="Center" VerticalAlignment="Center"/>
</Grid>
</Grid>

效果图：

看起来还不错，不过这个方案还是存在问题的，如果容器Grid本身是自增长的，那么杯具就开始了：

    <Grid>
<Grid HorizontalAlignment="Center" VerticalAlignment="Center" x:Name="g">
<Canvas>
<Rectangle RadiusX="5" RadiusY="5"
Width="{Binding ElementName=g, Path=Width}"
Height="{Binding ElementName=g, Path=Height}"
Stroke="Blue" StrokeDashArray="5,2,1,2" StrokeThickness="2"/>
</Canvas>
<TextBlock Text="aaa" HorizontalAlignment="Center" VerticalAlignment="Center"/>
</Grid>
</Grid>

效果图：

可以发现，Grid使用了自增长的方式，Binding也只能获得错误的Width和Height，也就是0，不过别担心，WPF还提供了ActualWidth和ActualHeight：

    <Grid>
<Grid HorizontalAlignment="Center" VerticalAlignment="Center" x:Name="g">
<Canvas>
<Rectangle RadiusX="5" RadiusY="5"
Width="{Binding ElementName=g, Path=ActualWidth}"
Height="{Binding ElementName=g, Path=ActualHeight}"
Stroke="Blue" StrokeDashArray="5,2,1,2" StrokeThickness="2"/>
</Canvas>
<TextBlock Margin="10,7,10,7" Text="aaa" HorizontalAlignment="Center" VerticalAlignment="Center"/>
</Grid>
</Grid>

效果图：

哈哈，圆满达成目标。

文中的方案为原型，如果要实用，还是建议用上模板：

<Style TargetType="ContentControl" x:Key="myBorder">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate>
                <Grid x:Name="g"
                      Background="{TemplateBinding ContentControl.Background}"
                      Width="{TemplateBinding ContentControl.Width}"
                      Height="{TemplateBinding ContentControl.Height}">
                    <Canvas>
                        <Rectangle RadiusX="5" RadiusY="5"
                                   Width="{Binding ElementName=g, Path=ActualWidth}"
                                   Height="{Binding ElementName=g, Path=ActualHeight}"
                                   Stroke="{TemplateBinding ContentControl.BorderBrush}"
                                   StrokeDashArray="5,2,1,2"
                                   StrokeThickness="{TemplateBinding ContentControl.BorderThickness}"/>
                    </Canvas>
                    <ContentPresenter Margin="5" Content="{TemplateBinding ContentControl.Content}"/>
                </Grid>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

然后就可以这样使用：

<ContentControl Margin="10" HorizontalAlignment="Center" VerticalAlignment="Center"
                BorderThickness="2" BorderBrush="Blue" Style="{StaticResource myBorder}">
    <TextBlock Text="abc"/>
</ContentControl>
<ContentControl Margin="10" HorizontalAlignment="Center" VerticalAlignment="Center"
                BorderThickness="3" BorderBrush="Red" Style="{StaticResource myBorder}">
    <CheckBox>check box</CheckBox>
</ContentControl>
<Button Margin="10" HorizontalAlignment="Center" VerticalAlignment="Center">
    <ContentControl BorderThickness="1" BorderBrush="Green" Style="{StaticResource myBorder}">
        check box
    </ContentControl>
</Button>

效果图为：

原文地址：http://www.cnblogs.com/vwxyzh/archive/2011/12/17/2291256.html